The field of the invention relates generally to electric machines and, more particularly, to a liquid cooled electric machine.
Electric machines such as motors and generators are used in many applications. However, there are still areas where the use of electric machines remains impractical, for example for use as the main drive of a vehicle such as an automobile or truck. Some known electric motors are generally too large and heavy and produce too little power for commercial use in such a vehicle.
One problem associated with electric machines is that it is necessary to cool them because they generate heat, which reduces their efficiency. Motor components such as the rotor, stator and stator windings are subjected to high temperatures and substantial thermal stresses. Accordingly, efficient motor cooling systems are necessary to prevent overheating of the motor components and to improve the overall electrical and mechanical performance of the motor. Some known electrical machines may be air cooled by blowing air through or over them, and other machines may be liquid cooled by spraying oil onto the rotor and stator assemblies or by directing oil through a shaft of the motor.